Song's team found that a 10 per cent increase in proteins from animals resulted in a 2 per cent increase in mortality overall, and an 8 per cent rise in death risk from heart disease. But a 3 per cent increase in protein from plants led to a 10 per cent decrease in mortality and a 12 per cent drop in risk of death from cardiovascular-related mortality.
The findings are clear, said Song, a research fellow at the hospital's clinical and translational epidemiology unit: plant-based proteins from sources such as beans, nuts, quinoa and seeds are a healthier choice than steaks or beef products such as hot dogs. That said, "I wouldn't suggest that everyone switch to vegan," Song added. That's because certain meats - chicken and fish, for example - also carried a much lower mortality risk overall and from heart disease.
But the traditional American diet, rife with animal products such as burgers, meatballs, meatloaf, steaks, eggs and dairy, "is associated with a variety of bad outcomes," Song said.
The research started in the 1980s and totalled "3.5 million person-years". In that time, there were 36,000 deaths among the participants - 13,000 from cancer, 9000 from cardiovascular disease and 14,000 from a mix of other causes.
"After adjustment for lifestyle and other dietary risk factors, a high consumption of protein from animal sources ... was weakly associated with an increased risk of death, while high consumption of protein from plant sources - breads, cereals, pasta, beans, nuts and legumes - was associated with a lower mortality rate," the statement said.
In some cases, it's not just that meat is bad and plants are good. Processed meats are filled with potentially unhealthy additives.
Song said he began the study because while others had suggested health benefits from a plant-based diet, none looked at the source of protein. "We were able to link information over the years," he said. The data from the two studies "provided a unique opportunity to look at long-term health outcomes".
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